Malonic Acid Diazoesters for C−H Insertion Crosslinking (CHic) Reactions: A Versatile Method for the Generation of Tailor‐Made Surfaces

Abstract

A simple and versatile method for the modification of a broad spectrum of surfaces with thin polymer films through the thermally or photochemically induced generation of surface‐attached polymer networks is reported. The system is based on copolymers containing diazomalonate groups, which can be activated by heat or light. To this end, the copolymers are deposited from solution onto solid substrates by standard techniques of thin‐film deposition (spin coating, dip coating). Upon activation the diazomalonate group decomposes and forms a carbene, which induces C−H insertion crosslinking (CHic) reactions. In the course of this process network formation and covalent surface attachment occur at the same time. The crosslinking process proceeds very rapidly, especially when the carbenes generated in the activation process cannot undergo Wolff‐rearrangement. The presented system can be used for the generation of a wide range of polymer layers and microstructures on a broad spectrum of surfaces.

Extending the Lotus Effect: Repairing Superhydrophobic Surfaces after Contamination or Damage by CHic Chemistry

“…On top of that, a thin layer of P­(FA- co -MAz) was deposited by simple dip-coating. The diazomalonate comonomer can act as a cross-linker that can be activated thermally and photochemically . Thus, it is able to form links between adjacent organic molecules via the nearly universal CHic process: , the only requirement that the reaction partner has to fulfill is that there are aliphatic C,H groups available.…”

“…During the UV exposure or a short heating to ≥150 °C, the diazo groups in the polymer become activated and form carbene intermediates, which can insert into practically any C,H bonds. This leads to the cross-linking of the deposited thin fluorinated film (CHic), rendering it completely insoluble . If organic moieties are present on the surface below the polymer film such as those present on the uncontaminated parts of the surface, the newly forming layer will also become covalently bound to the surface below.…”

Smooth and Transparent Films Showing Paradoxical Surface Properties: The Lower the Static Contact Angle, the Better the Water Sliding Performance

“…In particular, surfaces characterized by θ S values of water exceeding 150° or nearly 0° are referred to as superhydrophobic or superhydrophilic surfaces, respectively . It is commonly believed that water droplets spread out and stick to (super)­hydrophilic surfaces because of ionic or hydrogen bonding between the solid surface and the water droplet. , In an effort to reduce these interactions, (super)­hydrophobic treatments using low surface energy materials have been applied to various substrates. − Among the various (super)­hydrophobic treatments reported so far, to improve liquid (in this study, water) sliding or removing properties, minimizing CA hysteresis (Δθ: difference between advancing (θ A ) and receding (θ R ) CAs or Δθ cos : difference between cos θ R and cos θ A ) is key. , Where m : the mass of the water droplet, g : the gravitational constant, θ T : sliding/tilt angle, k : a constant that depends on droplet shape, w : the width of the water droplet, γ LV : the liquid (water)-vapor surface tension.…”

“Nickel Nanoflowers” with Surface-Attached Fluoropolymer Networks by C,H Insertion for the Generation of Metallic Superhydrophobic Surfaces

“…Moreover, because it is chemically anchored to the substrate, it cannot delaminate like a polymer layer attached solely by physical interactions. A strategy for creating surface-attached polymer networks that is nearly universally applicable is C,H insertion cross-linking (CHic; reaction shown in Figure b). − For this, copolymers containing a cross-linker comonomer are synthesized. When thin layers of these copolymers are deposited on a suitable surface, the cross-linker units within the glassy film become activated upon UV irradiation or heating, and reactive intermediates (carbenes, nitrenes, and triplet biradicals) are formed that undergo C,H insertion reactions with neighboring groups.…”

“…The result is a stable, surface-attached polymer network. (b) The CHic reaction via carbene intermediates: by photochemical or thermal activation of a diazo compound, N 2 is cleaved and a carbene is formed. This is capable of C,H insertion with neighboring aliphatic C,H groups.…”